Dual‐Metal Substitution Enabled NASICON‐Type Phosphate Cathodes With Enhanced Electrochemical Activity and Reaction Kinetics for Sodium‐Ion Batteries

Manganese substitution can increase the practical capacities of NASICON‐type Na ₃ V ₂ (PO ₄ ) ₃ /C cathodes owing to the high Mn ²⁺ /Mn ³⁺ activity and additional V ⁴⁺ /V ⁵⁺ activation. However, these Mn‐substituted NASICON‐type cathodes generally suffer from low reaction kinetics and unsatisfactory rate capability. In this study, a Mn/Al dual‐metal substitution strategy is utilized to design novel NASICON‐type cathodes with enhanced electrochemical performance by incorporating Al atoms into the Mn‐substituted Na _3.25 V _{2.75− x} Al _x Mn _0.25 (PO ₄ ) ₃ /C (NVAMP/C, 0 ≤  x  ≤ 0.2) system. The influence of Al content on the structural and electrochemical properties of the designed NVAMP/C materials is investigated by coupling various physical characterizations and electrochemical measurements. Experimental results reveal that the optimized NVAMP/C composition not only shows greatly high practical capacities of 122.0 mAh g ⁻¹ at 10 mA g ⁻¹ and 103.5 mAh g ⁻¹ at 1000 mA g ⁻¹ , but also exhibits robust cycling stability with 81.8% retention after 500 cycles at 100 mA g ⁻¹ . Furthermore, combined ex situ X‐ray diffraction, galvanostatic intermittent titration technique, and d Q /d V analysis confirm that the Mn/Al dual‐metal substitution regulates the phase‐evolution mechanism, thereby endowing the material with superior electrochemical reversibility and enhanced reaction kinetics. The finding suggests that the dual‐metal substitution strategy is effective in boosting the electrochemical properties of NASICON‐type cathodes for advanced sodium‐ion batteries.